Plasmodium falciparum malaria in the first year of life in an area of intense and perennial transmission

Abstract

SummaryA longitudinal study of Plasmodium falciparum malaria in infants in Idete village, south-eastern Tanzania, was conducted over a period of 14 months in order to determine the incidence of P. falciparum infection and clinical malaria in the first year of life. Of 1356 blood slides from cross-sectional surveys, 52.1% were positive for asexual stages of P. falciparum. There were marked increases in P. falciparum prevalence, parasite densities, overall fever incidence and the incidence of malaria fevers with age for the first 6 months of life. The average attack rate, estimated from a reversible catalytic model, was 0.029 per day with a slight increase with age but there was no initial period of protection against infection in neonates. Estimated average duration of infections was 64 days, with infections in older infants lasting much longer than those contracted during the first 2 months of life.These results support the hypotheses that the main effect of passively transferred maternal immunity to malaria is in the control of asexual stage parasites, and that the level of clinical immunity depends upon the extent of recent exposure to parasites. Infants as young as 4 months of age are at high risk of clinical attacks. Intervention programmes against malaria in areas of the highest transmission should therefore be designed to include this group.

10. Effect of insecticide-treated bed nets on the dynamics of multiple Plasmodium falciparum infections

“…1993SMITH et al,. , 1998aKITUA et al, 1996) and parasites usually cannot be detected by PCR in blood films found to be aparasitaemic by microscopy (FELGER et al, 1999b). As children grow older, parasite densities fall and the prevalence of microscopically sub-patent parasitaemia increases (FELGER et al.…”

“…Children under one year old form the age group most susceptible to clinical malaria in Kilombero (KITUA et al, 1996). In these children with the highest recovery rates, acute episodes of clinical malaria are positively associated with multiplicity of infection ).…”

Malaria infection and morbidity in infants in relation to genetic polymorphisms in Tanzania

“…In order to detect any differences in parasite densities or PCV levels of children with different genotypes or haemoglobin types, analysis of covariance, again with a random effect term were performed. Effects of age on parasite prevalence, density and PCV levels were reported previously (Kitua et al 1996), and age was included as a covariate in all present analyses.…”

“…Within a longitudinal study, consisting of epidemiological and parasitological surveys of malaria morbidity in the first year of life, 204 infants were randomly selected and followed for one year (Kitua et al 1996). Blood samples of the children were collected during household visits in eight cross-sectional surveys as previously reported (Kitua et al 1996).…”

“…Blood samples of the children were collected during household visits in eight cross-sectional surveys as previously reported (Kitua et al 1996). From the samples, packed cell volumes (PCV) were determined, by standard haematocrit centrifugation, and parasite densities were determined on thick and thin Giemsa stained blood films as described previously (Kitua et al 1996). Febrile episodes were recorded by passive case detection at the Idete dispensary (Alonso et al 1994;Kitua et al 1996).…”